Diving and snorkeling in San Antonio
Today, Wednesday, October 28, 2026 · local time (GMT-3) · Valparaíso, Chile Today, Wed, Oct 28 · GMT-3- Slack water
- 11:40 pm–12:20 am, 6:20–7:00 am, 12:10–1:00 pm and 5:50–6:40 pm
- Swell
- 3.1 ft, 11 s
- Water and suit
- 62.4 °F · 7 mm wetsuit
- Likely visibility
- Fair
- Water (satellite)
- Murky
Today, Wednesday, October 28, the best time to dive in San Antonio is 5:30 pm to 6:30 pm, with slack water at low tide, light wind and weak current, though with some swell. It's a good day (7/10). Visibility is likely fair. Water at 62.4–64.4 °F: a 7 mm wetsuit, with hood and booties. Today is the best day this week.
Your diving day in San Antonio at a glance
The strip runs from midnight to midnight, local time. Daylight on top; then the tide with its slack water (purple bands), the conditions hour by hour and the best times.
Today in detail
Likely visibility: fair- Slack water today: high tide 12:03 am (11:40 pm–12:20 am), low tide 6:41 am (6:20–7:00 am), high tide 12:33 pm (12:10–1:00 pm) and low tide 6:14 pm (5:50–6:40 pm)
- Likely visibility: fair. Swell (up to 4.2 ft at 9 s) over the last few days has stirred up the water. Based on the last 24 hours of data.
- Water at 62.4–64.4 °F: a 7 mm wetsuit, with hood and booties.
- Snorkeling: better not, with these waves, wind or current.
- Night dive: dark from 8:37 pm. Waning gibbous (92%), rising at 11:34 pm: a bright night.
How deep it gets off the shore
Shore diving works here: 33 ft at 0.4 mi and 66 ft at 0.8 mi from shore.
Source: NOAA ETOPO 2022 (CC0), cells of about 0.3 mi. For reference only: not for navigation or anchoring.
Slack water comes from the tide: in inlets, channels and between islands the water can keep running for an hour or two after. Ask the local dive shop.
Never dive alone and check with the local dive shop: this rating is a guide, not a substitute for a professional.
The water, as seen by satellite
The satellite saw murky water in the sea off San Antonio, within 3.1 mi (2 pixels of 2.5 mi; Kd490 = 1.33 m⁻¹). Kd490 measures how fast blue light fades with depth: the higher it is, the murkier the water, from plankton, suspended sand or rivers.
Very clear: under 0.06 m⁻¹ (open tropical sea: Red Sea, Caribbean). Clear: up to 0.12. Slightly murky: up to 0.25. Murky: above that (coasts with rivers, estuaries).
It's what the satellite saw that day, the last one without clouds: since then, swell, wind or rain may have changed it. The likely visibility above is today's.
Satellite: NOAA CoastWatch, Kd490 from the S-NPP VIIRS (experimental product), 2.5 mi pixels. It only shows where the seabed drops below 20 m close to shore: in shallower water the satellite sees the bottom and makes the water look murkier than it is. Sources and licenses
Diving forecast for the next 7 days
| Day | Rating | Best times | Swell | Visibility | Water |
|---|---|---|---|---|---|
| Today | 7 good day | 5:30–6:30 pm12:00–1:00 pm | 3.1 ft · 11 s | Fair | 62.4 °F · 7 mm wetsuit |
| Thu 29 | 7 good day | 5:40–8:00 pm12:30–2:20 pm | 3.4 ft · 8 s | Fair | 63.3 °F · 7 mm wetsuit |
| Fri 30 | 4 fair day | 12:50–3:50 pm6:40–8:10 pm | 5.0 ft · 12 s | Fair | 63.5 °F · 7 mm wetsuit |
| Sat 31 | 3 fair day | 1:50–4:50 pm8:40–11:30 am | 6.2 ft · 11 s | Poor | 64.4 °F · 5 mm wetsuit |
| Sun 1 | 3 fair day | 10:00 am–1:00 pm3:10–6:10 pm | 5.6 ft · 10 s | Poor | 64.4 °F · 5 mm wetsuit |
| Mon 2 | 3 fair day | 10:50 am–1:50 pm5:00–8:00 pm | 6.2 ft · 11 s | Poor | 63.5 °F · 7 mm wetsuit |
| Tue 3 | 3 fair day | 6:40–7:40 am6:40–8:20 pm | 5.8 ft · 11 s | Poor | 62.8 °F · 7 mm wetsuit |
Each day's rating comes from the swell, waves, wind, current, slack water, daylight and likely visibility. The forecast reaches about 7 days.
Dive sites, wrecks and dive shops nearby
Map: OpenFreeMap · © OpenMapTiles · © OpenStreetMap contributors
- ECIM Medio Fish seen: Scartichthys viridis, Cheilodactylus variegatus, Pinguipes chilensis, Aplodactylus punctatus 6.7 mi
- ECIM Reserve South Fish seen: Chromis crusma, Scartichthys viridis, Cheilodactylus variegatus, Pinguipes chilensis 6.8 mi
- Area Marina Costera Protegida Las Cruces 6.4 mi
Within 12 mi. Some may be missing or closed; marine reserves usually need a permit. Open the map on OpenStreetMap · Missing one? Add it to OpenStreetMap
Sites: © OpenStreetMap contributors (ODbL). Sites and fish: Reef Life Survey / IMOS NRMN, CC BY 4.0; fish names, Wikidata.
How we work out the diving rating
We score every moment of the day, every 10 minutes, from 0 to 10, with simple fixed rules:
- Swell: takes points away based on its height and period (a 10 s swell weighs 50% more than a 6 s one, because it reaches deeper and moves the bottom): nothing under 1.6 ft, up to 6.5 points from 9.8 ft. Surface waves count for getting in and out; we take the worse of the two.
- Wind: takes points away from force 4, about 12 mph (1 point), up to 6 points in a gale; half a point more when it blows offshore, because it pushes surface swimmers away from shore.
- Current: Météo-France's model current takes points away from half a knot (1 point) up to 6 points from 2 knots.
- Slack water: where we show the tide, up to 3 points come off when the water rises or falls fast (mid-tide, especially on spring tides) and none at slack, around each high and low tide.
- Light: half a point more with the sun high (3 hours either side of solar noon), 1.5 less at twilight and 3 less at night. Thunderstorms take away 5 and heavy rain 1.
- Likely visibility: good, fair or poor from the swell of the previous 48 hours, the rain of the previous 72 and the wind of the previous 24. Fair takes 1 point off the day's rating and poor, 2.
- Day's rating: the average of the best window (the stretch of 40 minutes to 3 hours with the best conditions), adjusted for likely visibility.
- Wetsuit, by water temperature: below 50 °F, drysuit; from 50 °F, 7 mm semi-dry; from 57 °F, 7 mm wetsuit; from 64 °F, 5 mm; from 72 °F, 3 mm; from 79 °F, shorty or rash guard.
Today: the best window scores 7.9 out of 10 and visibility is likely fair, so it takes 1 off.
It's an estimate from the swell, rain and wind of the previous days, not a measurement: real visibility also depends on the bottom, plankton and nearby rivers.
Separately, when there is data, the water clarity the satellite saw in the last few days (NOAA CoastWatch Kd490, 4 km pixels): it does not change the rating.
Slack water comes from the tide: in inlets, channels and between islands the water can keep running for an hour or two after. Ask the local dive shop.
It is a guide built from models, not a guarantee: every site has its own currents and bottom. Look at the water when you get there and ask the dive shop.
Before you get in the water
- Never dive alone: always with a buddy and, if you don't know the site, with a dive shop.
- Check with the local dive shop or club: they know the currents, the no-dive zones and how the water is today.
- Dive within your certification and experience, and stay within depth and no-decompression limits.
- Fly a dive flag (diver-down or alpha flag) on a float and watch for boat traffic.
- Marine reserves need a permit and often have quotas: ask before you go.
- This rating doesn't replace a professional's judgment or what you see when you arrive: if the sea doesn't look right, don't go in.
Questions about diving in San Antonio
Can you dive in San Antonio today?
Today is a good day (7/10). The best time is 5:30 pm to 6:30 pm, with slack water at low tide, light wind and weak current, though with some swell.
What about tomorrow? When's the best time to dive in San Antonio?
Tomorrow, Thursday, October 29: 5:40 pm to 8:00 pm, with a rating of 7/10.
Which day this week is best for diving in San Antonio?
Wednesday, October 28, at 7/10. Its best time is 5:30 pm to 6:30 pm.
When is slack water in San Antonio today?
Today the water barely runs at these times: high tide 12:03 am (11:40 pm–12:20 am), low tide 6:41 am (6:20–7:00 am), high tide 12:33 pm (12:10–1:00 pm) and low tide 6:14 pm (5:50–6:40 pm). It's an estimate from the tide: in inlets and channels slack water can come later. Ask the local dive shop.
What will the visibility be like in San Antonio?
Likely fair. Swell (up to 4.2 ft at 9 s) over the last few days has stirred up the water. Based on the last 24 hours of data. It's an estimate, not a measurement.
What wetsuit do I need to dive in San Antonio?
Water at 62.4–64.4 °F: a 7 mm wetsuit, with hood and booties. If you get cold easily or plan several dives, go thicker.
Can you dive at night?
Yes, with experience, a primary and a backup light, and ideally with a dive shop. Night dive: dark from 8:37 pm. Waning gibbous (92%), rising at 11:34 pm: a bright night.
How is the rating worked out?
From the swell and its period, the waves, the wind, the current, slack water, daylight and likely visibility. Each factor adds or takes away a fixed number of points and the rating sums up the best window of the day out of 10.
More about San Antonio today
Learn more
Our own calculation: tide from FES2022 (AVISO/CNES), sun and moon with astronomy-engine, and sea and weather from Open-Meteo (Météo-France, ECMWF, NOAA GFS and Copernicus Marine, CC BY 4.0). Dive sites: © OpenStreetMap contributors (ODbL). FES2022 Tide was produced by LEGOS, NOVELTIS and CLS, funded by CNES, and distributed by AVISO (https://doi.org/10.24400/527896/a01-2024.004), AVISO licence (https://www.aviso.altimetry.fr/fileadmin/documents/data/License_Aviso.pdf). Modified by TidePlanet: constants interpolated from the nearest model cells offshore; heights above mean sea level.